One of the nation's most influential judges and legal writers, Richard Posner, is retiring as of Saturday from the 7th U.S. Circuit Court of Appeals in Chicago.

Posner has written more than 3,300 opinions in nearly 36 years on the bench, along with scores of books. He is known for a sharp wit, clear writing and opinions that could be equally biting and humorous, with occasional references to his cats.

Posner said in a statement he is "proud to have promoted a pragmatic approach to judging... and to apply my view that judicial opinions should be easy to understand and that judges should focus on the right and wrong in every case."

The 7th Circuit's Chief Judge, Dianne Wood, calls Posner "one of the most distinguished people to ever sit on the federal bench," adding "His opinions have had an impact around the world."

Posner was appointed by President Ronald Reagan and was known as a conservative, although in recent years he became less so. He told NPR's Nina Totenberg, "I've become less conservative since the Republican Party started becoming goofy."

Posner is an outspoken critic of the U.S. Supreme Court and some of it's justices, once saying in an interview, "It's not a real court, it's a political court." The 78-year old says in his statement that he plans to continuing teaching at the University of Chicago Law School, as he has since 1969, and writing "with a particular focus on social justice reform."